Define sync strategy

[FikriMilano]

IMPORTANT: Where possible all PRs must be linked to a Github issue

Fixes #1512
Ideally, this is to be merged after #890

Checklist

• I have written Unit tests for any new feature(s) and edge cases for bug fixes
• I have added any strings visible on UI components to the strings.xml file
• I have updated the CHANGELOG.md file for any notable changes to the codebase
• I have run ./gradlew spotlessApply and ./gradlew spotlessCheck to check my code follows the project's style guide
• I have built and run the fhircore app to verify my change fixes the issue and/or does not break the app

[codecov]

Codecov Report

Merging #1569 (e2e87a2) into main (2748ebc) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main    #1569      +/-   ##
============================================
+ Coverage     52.20%   52.23%   +0.03%     
- Complexity      657      659       +2     
============================================
  Files           191      192       +1     
  Lines          6793     6798       +5     
  Branches       1216     1216              
============================================
+ Hits           3546     3551       +5     
+ Misses         2645     2644       -1     
- Partials        602      603       +1     

Flag	Coverage Δ
engine	65.52% <100.00%> (+0.04%)	⬆️
quest	33.30% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...smartregister/fhircore/engine/sync/SyncStrategy.kt	100.00% <100.00%> (ø)
...egister/fhircore/quest/ui/main/AppMainViewModel.kt	49.48% <0.00%> (ø)

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